Microsoft has pulled its Windows 7 promotional pricing in a move that will no doubt be unpopular with those not quick off the mark in ordering the new operating system.

Microsoft's promotional, pre-sales, pre-order pricing for its next operating system went live in the UK on 15 July and was scheduled to run up until 14 August.

However, that move appears to have changed with Microsoft and Amazon boosting their prices to cash in on the new found popularity of the OS.

Microsoft was offering the pre-sales price of £49.99 and £99.99, however is now charging £79.99 for Home Premium and £189.99 for Professional upgrade editions.

While problems with its online store going down marred the debut day for the pre-order sales, Microsoft is likely to make many more consumers unhappy by ending the promotion within 2 days.

Microsoft did state that the lower pricing was a "special time limited offer" and "while stocks last", but the shock withdrawal of the promo offer, and the online store issues have led some conspiracy theorists to suggest Microsoft wanted to sell as few copies as it could at the affordable price point.

Amazon, who reported strong sales as Windows 7 went on sale, has also reached the end of its allocation of the lower-priced operating system.

A Microsoft spokesperson would not reveal to us what the allocation of promotional price stock was.

Amazon has issued a statement about the situation, citing "exceptionally high demand".

"Windows 7 Home Premium and Windows 7 Professional became available for pre-order yesterday at a special introductory price while stocks lasted. We encountered an exceptionally high demand for these products and sold more copies of Windows 7 in its first eight hours of availability than we did copies of Windows Vista throughout its entire 17-week pre-order period. As a result, we have sold out of our allocation of copies of Windows 7 at the special introductory price and are now selling at a pre-order price of £74.97 for the Window 7 Home Premium and £179.97 for Windows 7 Professional".